In order to be able to offer healthy ambient conditions to the crew of closed habitats, e.g. submarines or space stations, the concentrations of volatile organic substances, also termed volatile organic compounds (VOCs) must be kept low. VOCs are usually formed by outgassing from materials, leaks, or by metabolic processes of the crew.
For air conditioning the contained air in closed habitats, usually refrigerants (e.g.,. R134a® (1,1,1,2-tetrafluoroethane)) are used as working medium in the cooling units, e.g. air conditioning units. Via leaks, the refrigerant can pass into the contained air. Also, owing to maintenance and repair work on the cooling units, refrigerant can pass into the contained air.
Usually, in closed habitats, activated carbon is used for binding harmful gases, in particular VOCs. However, R134a® (1,1,1,2-tetrafluoroethane) is a particularly stable molecule which, in addition, can only be adsorbed to activated carbon in very low amounts. The loading in usual contained air conditions around 25° C., 60% relative humidity and 1 bar is approximately 0.1% by weight. In known techniques for decomposing R134a® (1,1,1,2-tetrafluoroethane) catalytically at high temperatures and with input of energy, toxic gases, such as hydrogen fluoride, for example, are released, which themselves must be safely removed or bound.
U.S. Pat. No. 3,507,051 and EP 0 381 942 A1 disclose methods for regeneration of adsorbers. Kirk-Othmer: Encyclopedia of Chemical Technology, Fourth Edition, John Wiley Sons, New York 1991, Vol. 1, ISBN 0-471-52669-X, pp. 546-557 describes the principles of the temperature swing technique and also of the pressure swing technique.
Methods are certainly known for removing R134a (1,1,1,2-tetrafluoroethane) from refrigeration units by suction, but here R134a® (1,1,1,2-tetrafluoroethane) is present in a virtually pure concentration. In the contained air in closed habitats, the R134a® (1,1,1,2-tetrafluoroethane) concentration, however, must be kept below the permissible limiting values (100-200 ppm). For this purpose no methods are known which bind R134a® (1,1,1,2-tetrafluoroethane) in a technically useful manner without large losses of air.
It is the object of the invention to provide a regenerative method with which volatile organic substances can be bound and removed from the contained air of closed habitats. A further object is the indication of a corresponding device.